Method and apparatus for scanning and monitoring the roof of seams mined by cutting machines



March 5. 1968 KARL-HEINZ WEBER 3,371,964

METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINEDBY CUTTING MACHINES Filed June 20, 1966 4 Sheets-Sheet 1 FIG. I.

WWWWWWWWWW INVENTOR Karl-Heinz Weber March 5. 1968 KARL-HEINZ WEBER3,371,964

METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINEDBY CUTTING MACHINES Filed June 20, 1966 4 Sheets-Sheet 2 z M 2:- WW 2, z

March 5, 1968 KARL-HEINZ WEBER METHOD AND APPARATUS FOR SCANNING ANDMONITORING THE ROOF OF SEAMS MINED BY CUTTING MACHINES Filed June 20,1966 4 Sheets$heet 5 ULTRASONIC ULTRASONIC PULSE PULSE RECEIVERTRANSMITTER TRANSMITTER GENERATOR ,2? AMPLIFIER INTEGRATOR ERROR A9SIGNAL STAGE ELL Q POWER SUPPLY a RECORDING 42 TRANsIsTOR CONTROLINSTRUMENT STAGE MEANS I I I I F|G.3.

1.1 L1 1.] LJ 1.!

March 5. 1968 KARL-HEINZ WEBER 3,371,964

METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINEDBY CUTTING MACHINES Filed June 20, 1966 4 Sheets-Sheet 4 (D N) m m s 9|$1 l 2 ml E z a w w u WW 0 United States Patent Ofiice 3,371,964Patented Mar. 5, 1968 3,371,964 METHOD AND APPARATUS FOR SCANNING ANDMONITORING THE ROOF OF SEAMS MINED BY CUTTING MACHINES Karl-Heinz Weber,Witten-Heven, Germany, assignor to Gebr. Eickhoif, Maschinenfabrik andEisengiesserei m.b.H., Bochum, Germany, a corporation of Germany FiledJune 20, 1966, Ser. No. 558,727 Claims priority, application Germany,June 30, 1965, E 29,612 5 Claims. (Cl. 2991) This invention relates tomechanized mining of veins, such as the mechanized longwall method ofmining coal seams and, more particularly, to scanning and monitoring theroof of the seams while mining is in progress, and to suitable scanningapparatus.

In the mining of coal veins, for example by the mechanized longwallmining method, it is known to employ cutting machines that out along thelongwall face of the coal seam while moving longitudinally along saidlongwall face on a guideway or track placed therealong. A suitablecutting machine for performing this operation comprises essentially amachine body movable on said guideway, and a pair of support armspivotally attached to the body and carrying respectively two cuttingtools, for example cutting rollers, hereinafter referred to also asupper and lower cutting tools. As the cutting machine advances along thelongwall face, the lower cutting roller works the floor of the coalsea-m while the upper cutting tool works the upper seam portion therebyexposing the seam roof. In cutting machines of this type, the uppercutting tool may be designed to follow automatically the seam roof ofveins varying in thickness. For example, the upper cutting tool may becontrolled in response to scanning the seam roof with a radiation beamfrom an isotope.

In mechanical mining operations, with no attendant present at the seamface, the conveyor means or haulagev equipment for taking up the coalmined by the cutting machine and hauling it away is advancedmechanically toward the face of the seam, usually by cylinder means,before commencing with the next cut along the longwall face. Thisoperation is controlled from the roadway at which the longwall faceusually terminates, the roadway as a rule, but not necessarily,extending substantially perpendicularly to the longwall face. The roofsupport structure, likewise, is advanced mechanically toward thelongwall face before performing the next cut therealong. The sequence oferecting and advancing the support structure toward the coal face,completing a cut along said face, again advancing the support structure,completing the next cut, and so on, is similar to that practiced inmanual mining operations, whereby in the advanced position of thesupport structure, the upper beams thereof, usually referred to as caps,extend sulficiently far so as to support the seam roof above theguideway, haulage equipment and the cutting machine without, however,interfering with the cutting action of the upper cutting tool during thenext out along the longwall face.

When the seam roof is of poor quality, the mining equipment breaks notonly the coal but occasionally also portions of the overburden, thusproducing breaks and cavities that extend sometimes deep into the seamroof. As a result, the support structure might fail to provide adequateprotection against any rocks that might fall from such cavities anddamage the cutting machine and other equipment.

It is an object of the present invention to prevent damage to theequipment that might occur as a result of seam roofs of poor quality orirregularities therein.

The invention, briefly, accomplishes this object by scanningcontinuously the shape or contour of the seam roof and observing arecording that is representative of the seam roof contour at a stationremote from the coal face. Preferably, the recording is a visual displayof the seam roof contour, and the remote observation station is in theroadway. The invention thus facilitates shutting down of the equipmentbefore damage thereto might occur. If de-' sired, the equipment may beshut down automatically by rendering the control means for the equipmentresponsive to signals that vary with the recording.

A specific embodiment of this invention resides in a method of scanningand monitoring the roof of a seam that is mined by a cutting machinehaving a machine body and a support arm pivotally attached to themachine body and carrying acutting tool for cutting and exposing theseam roof as the cutting machine advances along the face of the seam,said method comprising the steps of measuring continuously the height ofthe seam roof as determined by the inclination of the support armcarrying the cutting tool that follows and exposes the seam roof whilecutting along the face is in progress, determining the height of theseam roof that had been exposed by a previous cut along the face bymeans of ultrasonic altimeter means disposed on the cutting machine forscanning the seam roof, and recording an error signal which isrepresentative of the difference between the two height values obtained.

In the specific embodiment more fully described hereinafter, errorsignals of one, say positive, polarity are obtained when the seam roofrises in the direction the cutting machine is advancing along the faceof the coal seam. Error signals of the opposite polarity are obtainedwhen the seam roof declines in the direction the cutting machineadvances. The error signal is zero when the seam roof is substantiallylevel in the advancing direction. Since, as mentioned above, during thecut along the face of the seam, the caps of the support structureprovide support for the roof straight above the cutting machine andhaulage equipment, the scanning ultrasonic waves pick up also said caps,thus facilitating also to monitor the proper location of the caps.

A suitable apparatus for carrying out the novel scanning and monitoringmethod comprises essentially: a variable impedance means responsive tothe inclination of the pivotally attached support arm carrying thecutting tool exposing the seam roof for producing a first signalrepresentative of the height of the seam roof where exposed by thecutting tool; an ultrasonic transmitter disposed on the body of thecutting machine for transmitting ultrasonic waves to scan the seam roof;an ultrasonic receiver arranged to receive the waves reflected by theseam roof and an integrator for producing a second signal representativeof the height of the scanned sea-m roof; an error signal stage forcombining the first and second signals and producing an error signal; anindicating instrument including a recording drum and being located at astation remote from the mining stat-ion; an electrical connectionbetween the error signal stage and the indicating instrument; and adrive for rotating the recording drum, said drive being responsive tothe main drive for advancing the cutting machine along the face of theseam.

The indicating instrument is located preferably in the roadway. Theelectrical connection between the error signal and the indicatinginstrument is preferably included in the utility cable that may alsocontain the power supply and control conductors for the drive means ofthe cutting tools. The variable impedance means may be a potentiometer.

In order to monitor the contour of the seam roof even more precisely,two ultrasonic altimeter means, each including a transmitter andreceiver, may be disposed sideby-side on the body of the cutting machinefor scanning the seam roof at different distances respectively from the'face of the seam. Each altimeter means is associated with a separateintegrator and a separate error signal stage, the two error signalstages being connected to the indicating instrument. The apparatusotherwise is similar to that described above, i.e., each error signalstage is connected to the variable impedance means so as to combine thesignal from the associated integrator with that from said impedancemeans; thus two error signals are produced which are recordedsimultaneously by the indicating instrument, the recordings visuallyindicating whether the seam roof rises, declines, or remainssubstantially level as the cutting machine advances along the face whilecutting is in progress.

Further advantages and objects of the present invention will become morereadily apparent from the following description and the accompanyingdrawings, in which:

FIGURE 1 is a side view of a cutting machine as it advances along theface of a scam, the machine being equipped with ultrasonic altimetermeans in accordance with this invention;

FIG. 2 is an elevation view of a similar cutting machine as it cutsalong the longwall face of the seam toward the roadway in which maindrive means, power supplies and control means for the mining equipmentare located;

FIG. 3 shows schematically various elements of a monitoring apparatus inaccordance with the present invention;

FIG. 4 shows a diagram as recorded by the indicating instrument; and

FIG. 5 shows a modification, similar to FIG. 2, with the exception,however, that two ultrasonic altimeter means are disposed on the cuttingmachine.

Referring to FIGS. 1 and 2, the arrow denotes the direction in which thecutting machine 11 advances along the longwall face of the seam. In theillustrated embodimerit the haulage equipment includes a track orguideway 12 on which the machine 11 is movable in either direction alongthe longwall face. The cutting machine which per se forms no part of thepresent invention, comprises essentially a machine body or carriage 11a,a lower support arm 13 pivotally attached to the body 11a and carrying alower cutting roller 14 for working the floor of the coal seam, and anupper support arm 15 pivotally attached to the machine body and carryingan upper cutting roller 16 for working the upper portion of the seam andexposing the seam roof, i.e., the machine is so designed that the uppercutting roller may follow the seam roof. When cutting in the directionopposite to that indicated by the arrow 10 is desired, the support arms13 and 15 are pivotally moved upwardly and downwardly respectively suchthat the roller 16 works the floor and the roller 14 the upper portionof the coal seam. While cutting along the face is in progress the caps17 of the support structure (not otherwise shown, except for the supportposts 17a in FIGS. 2 and 5) support the overburden 18 and extendsufficiently far toward the face of the seam so as to support also theoverburden directly above the machine body 11a and the haulage equipmentincluding the track 12 without, however, interfering with the cuttingaction of the cutting rollers. FIG. 1 shows a cavity 19 in the seam roof20. In accordance with this invention an ultrasonic altimeter means 21including a transmitter 22 and a receiver 23 (FIG. 3), is disposed onthe machine body 11a.

Referring now to FIG. 3, the apparatus for carrying out the scanning andmonitoring method in accordance with this invention includes a pulsegenerator 24 connected through a pulse transmitter 24a to energize theultrasonic transmitter 22 for producing ultrasonic waves that scan theseam roof as the cutting machine 11 advances along the face of the seam.The ultrasonic receiver 23 is designed for receiving the waves reflectedby the seam roof and has its output connected to an integrator 26through an amplifier 27, the integrator 26 being designed for producingan electrical signal that varies with the height of the scanned seamroof. A variable impedance means in the form of a potentiometer 28 isresponsive to the in clination of the arm 15 that varies with thethickness of the seam; hence, the impedance means is capable ofproviding a signal that varies with the height of the seam roof wherecontacted and exposed by the upper cutting tool 16. The two signals arecombined in the error signal stage 29 to produce an error signal that isapplied through the electrical connection 30 in the utility cable 31 tothe control and power supply means 32 for the cutting ma chine, themeans 32 being located in the roadway 33, FIG. 2. The means 32 isconnected through the electrical connection 34 to an indicatinginstrument 35 which includes a rotatable recording drum.

In operation, longitudinal advancement of the cutting machine 11 alongthe longwall face 36 of the coal seam 37 is accomplished by tractionmeans which in the shown embodiments comprises a drag chain 38, FIG. 2,attached to the machine body and extending therefrom to a drum 39 of awinch 40. The recording drum of the instrument 35 is operatively coupledto the drum 39 by means known in the art, for example, through aspeed-responsive signal producing means 41, a transistor stage 42 and anelectrical connection 43, thereby effecting rotation of the recordingdrum corresponding to the longitudinal motion of the cutting machine.

Referring now to FIG. 4, the abscissa denotes the direction ofadvancement of the cutting machine along the longwall face 36 and,hence, gives a measure of the length of the face 36. The ordinateindicates the magnitude of the error signals from the error signal stage29, i.e., the shown diagram represents the error signals over the lengthof the face mined. The substantially horizontal portion of the curveindicates that over the corresponding section of the longwall face theseam roof is substantially level, the small rectangular indentationsindicating the 10- cations of the caps 17 in FIG. 1. The ascendingright-hand portion of the curve corresponds to the cavity 19 in FIG. 1.By observing the continuously recorded curve the attendant is thereforeenabled to detect irregularities in the seam roof and, if deemedadvisable, to shut down the cutting machine before any damage theretooccurs.

Referring to FIG. 5, the cutting machine 11 is equipped with twoultrasonic altimeter means 21a and 21b, each including a transmitter andreceiver, disposed side-by-side on the machine body for scanning theseam roof at different distances respectively from the face of the seam.Otherwise FIG. 5 is similar to FIG. 2, like reference numerals beingemployed in both figures to denote the same elements. Each of thealtimeter means 21a and 21b is associated with a separate integrator anda separate error signal stage in the manner previously described, thetwo error signal stages providing two error signals that are recorded bythe indicating instrument. The simultaneous recording of the two errorsignals are indicative of the course of the seam roof in both thedirection parallel to the face of the seam and the directionperpendicular thereto.

While the invention has been shown in connection with specificembodiments, it will be apparent to those skilled in the art thatvarious modifications may be made without departing from the spirit andscope thereof. For example, the operation of the cutting machine may becontrolled in response to said error signal. Thus automatic shut down ofthe cutting machine may be accomplished by rendering the control portionof the aforesaid control and power supply means responsive to the errorsignals, i.e., the control means may be adjusted for automatic shut downin response to the error signals exceeding a predetermined magnitude.

I claim as my invention:

1. Method of scanning and monitoring the roof of a seam mined by acutting machine having a support arm carrying a cutting tool for cuttingthe seam along a face thereof and following the seam roof to expose thelatter as the cutting machine advances along the face of the seam, saidmethod comprising the steps of producing a first signal in response tothe inclination of said support arm while cutting along the seam face isin progress, scanning a portion of the seam roof exposed by a previousout along the face of the seam by means of ultrasonic altimeter meansdisposed on the cutting machine, producing a second signal responsive tosaid ultrasonic altimeter means, and recording continuously thedifference between said first and second signals while cutting along theseam face is in progress.

2. The method of claim 1, including the step of controlling theoperation of said cutting machine in response to an error signal derivedfrom the difference of said first and second signals.

3. Apparatus for scanning and monitoring the roof of a seam mined by acutting machine having a support arm carrying a cutting tool for cuttingthe seam along a face thereof and following the seam roof to expose thelatter, said apparatus comprising an adjustable impedance meansresponsive to the inclination of the support arm for producing a firstsignal, ultrasonic altimeter means including a transmitter and receiverdisposed on the cutting machine for scanning a previously exposedportion of the seam roof as the cutting machine cuts along the seamface, integrator means responsive to said altimeter means for providinga second signal, an error signal stage for combining said first andsecond signals and producing an error signal, and indicating meanslocated at a station remote from the cutting machine and being elec- 3Otrically connected to said error signal stage for recording continuouslythe error signal.

4. The apparatus of claim 3, wherein a second ultrasonic altimeter meansis disposed on the cutting machine side-by-side with the first-mentionedultrasonic altimeter means for scanning the seam roof along a pathparallel substantially to the seam face at a distance therefromsubstantially different from that between the seam face and thefirst-mentioned altimeter means; said apparatus including secondintegrator means responsive to said second altimeter means for producinga third signal, and a second error signal stage for combining said firstand third signals and producing a second error signal, said second errorsignal stage being electrically connected to said indicating means forrecording the second error signal simultaneously with thefirst-mentioned error signal.

5. The apparatus of claim 3, wherein said indicating means comprises arecording drum operatively coupled to the cutting machine for rotationalmovement corresponding to the motion of the cutting machine along theseam face while cutting is in progress.

References Cited UNITED STATES PATENTS 2,761,666 9/ 1956 Heimaster et al2991 3,108,789 10/1963 Heimaster et al 299-1 FOREIGN PATENTS 966,714 8/1964 Great Britain.

ERNEST R. PURSER, Primary Examiner.

1. METHOD OF SCANNING AND MONITORING THE ROOF OF A SEAM MINED BY ACUTTING MACHINE HAVING A SUPPORT ARM CARRYING A CUTTING TOOL FOR CUTTINGTHE SEAM ALONG A FACE THEREOF AND FOLLOWING THE SEAM ROOF TO EXPOSE THELATTER AS THE CUTTING MACHINE ADVANCES ALONG THE FACE OF THE SEAM, SAIDMETHOD COMPRISING THE STEPS OF PRODUCING A FIRST SIGNAL IN RESPONSE TOTHE INCLINATION OF SAID SUPPORT ARM WHILE CUTTING ALONG THE SEAM FACE ISIN PROGRESS, SCANNING A PORTION OF THE SEAM ROOF EXPOSED BY A PREVIOUSCUT ALONG THE FACE OF THE SEAM BY MEANS OF ULTRASONIC ALTIMETER MEANSDISPOSED ON THE CUTTING MACHINE, PRODUCING A SECOND SIGNAL RESPONSIVE TOSAID ULTRASONIC ALTIMETER MEANS, AND RECORDING CONTINUOUSLY THEDIFFERENCE BETWEEN SAID FIRST AND SECOND SIGNALS WHILE CUTTING ALONG THESEAM FACE IS IN PROGRESS.